sorry maybe my explanation wasn't pretty good.
my isp doesn't block port 80, that i am sure of, i already made a server running on this router and the port forwarding are set to forward port 80 to my server, the problem is that usually when you install ispconfig3 and you type 192.168.1.100 the index.html isn't suppose to be the one from apache but the welcome from ispconfig3, in my case it is the It works! from apache. when i try domain.com i get a page server not found. ispconfig doesn't seems to link to apache2.